Preparing to install Fuchsia on Pixelbook

Update ChromeOS

If your Pixelbook has never been booted, it is best to boot it normally to check for any critical updates, as follows:

  1. Boot the Pixelbook normally. Opening the lid usually powers on the device. If this doesn't work, the power button is on the left side of the device, near the front of the wrist rest.
  2. Tap the “Let's go” button.
  3. Connect to a wired or wireless network.
  4. Accept the terms to proceed to the update check step.
  5. The device should check for updates, install any found.
  6. After rebooting from any updates, tap ‘Browse as Guest’ in the lower left corner.
  7. From the browser UI, go into “Settings->About Chrome OS” or “Help->About Chrome OS” and confirm the version is >=62.

Put your device into developer mode

WARNING: This will erase any state stored locally on your Pixelbook

  1. Power off the Pixelbook.
  2. Go into Recovery Mode. Hold down Esc+Refresh (first and third buttons on the top row of the keyboard). Then press the Power button (bottom left side of the device).
  3. Start by disabling OS verification by pressing Ctrl+D. You should see “To turn OS verification OFF, press ENTER”. Press Enter to confirm.
  4. When your device reboots, you'll get confirmation that OS verification is OFF. Press Ctrl+D again to enter Developer Mode.
  5. Wait for the device to re-configure itself, which will take several minutes. Initially it may not appear to be doing anything. Let the device sit for a minute or two. You will hear two loud <BEEP>s early in the process. The process is complete when you hear two more loud <BEEP>s.
  6. The device should reboot itself when the Developer Mode transition is complete. You can now jump to Step #2 in the “Boot from USB” section.

Boot from USB

  1. Boot into ChromeOS.
  2. You should see a screen that says “OS verification is OFF” and approximately 30 seconds later the boot will continue. Wait for the Welcome or Login screen to load. Ignore any link for “Enable debugging features”.
  3. Press Ctrl+Alt+Refresh/F3 to enter a command shell. If pressing this key combination has no effect, try rebooting the Pixelbook once more.
  4. Enter ‘chronos’ as the user with a blank password
  5. Enable USB booting by running sudo crossystem dev_boot_usb=1
  6. (optional) Default to USB booting by running sudo crossystem dev_default_boot=usb.
  7. Plug the USB drive into the Pixelbook.
  8. Reboot by typing sudo reboot
  9. On the “OS verification is OFF” screen press Ctrl+U to bypass the timeout and boot from USB immediately. (See Tips and Tricks for other short circuit options)

The USB drive is only needed for booting when you want to re-pave or otherwise netboot the device. If you didn‘t make USB booting the default (Step #6), you will need to press Ctrl+U at the grey ‘warning OS-not verified’ screen to boot from USB when you power on your device. If the device tries to boot from USB, either because that is the default or you pressed Ctrl+U, and the device fails to boot from USB you’ll hear a fairly loud <BEEP>. Note that ChromeOS bootloader USB enumeration during boot has been observed to be slow. If you're having trouble booting from USB, it may be helpful to remove other USB devices until the device is through the bootloader and also avoid using a USB hub.

Tips and Tricks

By default the ChromeOS bootloader has a long timeout to allow you to press buttons. To shortcut this you can press Ctrl+D or Ctrl+U when on the grey screen that warns that the OS will not be verified. Ctrl+D will cause the device to skip the timeout and boot from its default source. Ctrl+U will skip the timeout and boot the device from USB.

Going back to ChromeOS

To go back to ChromeOS you must modify the priority of the Fuchsia kernel partition to be lower than that of at least one of the two ChromeOS kernel partitions.

  1. Press Alt+Esc to get to a virtual console

  2. Find the disk that contains the KERN-A, KERN-B, and KERN-C partitions with the lsblk command. Below this is device 000, note how the device path of the kernel partitions is an extension of that device.

     $ lsblk
     ID  SIZE TYPE             LABEL                FLAGS  DEVICE
     000 232G                                              /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block
     001   5G data             STATE                       /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-000/block
     002  16M cros kernel      KERN-A                      /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-001/block
     003   4G cros rootfs      ROOT-A                      /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-002/block
     004  16M cros kernel      KERN-B                      /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-003/block
     005   4G cros rootfs      ROOT-B                      /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-004/block
     006  64M cros kernel      KERN-C                      /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-005/block
     007   4G cros rootfs      ROOT-C                      /dev/sys/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-006/block
  3. Use the gpt command to look at the device's (eg. 000) partition map.

     $ gpt dump /dev/class/block/000
     blocksize=0x200 blocks=488554496
     Partition table is valid
     GPT contains usable blocks from 34 to 488554462 (inclusive)
     Paritition 0: STATE
         Start: 478035968, End: 488521727 (10485760 blocks)
         id:   51E8D442-0419-2447-96E5-49CB60CF0B25
         type: EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
         flags: 0x0000000000000000
     Paritition 1: KERN-A
         Start: 20480, End: 53247 (32768 blocks)
         id:   054CD627-F23C-5C40-8035-C188FA57DE9C
         type: FE3A2A5D-4F32-41A7-B725-ACCC3285A309
         flags: priority=2 tries=0 successful=1
     Paritition 2: ROOT-A
         Start: 8704000, End: 17092607 (8388608 blocks)
         id:   936E138F-1ACF-E242-9C5B-3667FAA3C10C
         type: 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC
         flags: 0x0000000000000000
     Paritition 3: KERN-B
         Start: 53248, End: 86015 (32768 blocks)
         id:   A8667891-8209-8648-9D5E-63DC9B8D0CB3
         type: FE3A2A5D-4F32-41A7-B725-ACCC3285A309
         flags: priority=1 tries=0 successful=1
     Paritition 4: ROOT-B
         Start: 315392, End: 8703999 (8388608 blocks)
         id:   8B5D7BB4-590B-E445-B596-1E7AA1BB501F
         type: 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC
         flags: 0x0000000000000000
     Paritition 5: KERN-C
         Start: 17092608, End: 17223679 (131072 blocks)
         id:   C7D6B203-C18F-BC4D-9160-A09BA8970CE1
         type: FE3A2A5D-4F32-41A7-B725-ACCC3285A309
         flags: priority=3 tries=15 successful=1
     Paritition 6: ROOT-C
         Start: 17223680, End: 25612287 (8388608 blocks)
         id:   769444A7-6E13-D74D-B583-C3A9CF0DE307
         type: 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC
         flags: 0x0000000000000000
  4. KERN-C typically hosts the Zircon kernel. KERN-A and KERN-B typically have ChromeOS kernels. To go to ChromeOS we need to lower the priority of KERN-C here by referencing the partition index on the disk that has that partition.

     $ gpt edit_cros 5 -P 0 /dev/class/block/000
  5. Reboot

To go back to the Fuchsia kernel, just re-pave the device.